Ceteareth-2 to -18, and Ceteareth-22, help to form emulsions by reducing the surface tension of the substances to be emulsified. Ceteareth-22 is also used to decrease the thickness of liquid cosmetics and personal care products. Ceteareth-20 to -40 help other ingredients to dissolve in a solvent in which they would not normally dissolve, and along with Ceteareths-50 to -100, clean the skin and hair by helping water to mix with oil and dirt so that these substances can be rinsed away.

Scientific Facts:

Ceteareths are made from cetearyl alcohol, which is a mixture of cetyl and stearyl alcohol, and ethylene oxide. The numerical value represents the average number of molecules of ethylene oxide added to generate the specific Ceteareth ingredient. For example, Ceteareth-2 is made by reacting Cetearyl Alcohol with an average of 2 molecules of ethylene oxide.

CIR Safety Review: The CIR Expert Panel considered previous findings from the safety assessment of Polyethylene Glycol (PEG), several fatty alcohols (Cetearyl Alcohol, Cetyl Alcohol, and Stearyl Alcohol), and Steareths to supplement the data on the Ceteareth ingredients. These data indicated little evidence of toxicity. Data on the PEG ingredients indicated that when used on burn patients, PEGs may result in kidney effects. Therefore, the CIR Expert Panel also concluded that the Ceteareth ingredients should not be used on damaged skin.

Ceteareth-15 (10% in formulation) was minimally irritating after a single dermal exposure. In clinical studies, Ceteareth-15 (1.5% in formulation) produced minimal irritation when tested in both 4- and 21-day patch tests, and was not a sensitizer when tested (1.35% in formulation) in a repeat-insult patch test. Small amounts of 1,4-dioxane, a by-product of ethoxylation, may be found in the Ceteareth ingredients. The potential presence of this material is well known and can be controlled through purification steps to remove it from the ingredients before blending into cosmetic formulations.

Ceteareths are the polyethylene glycol esters of Cetearyl Alcohol. The properties of Ceteareths are dependent on the degree of polymerization of the polyethylene glycol segment. In cosmetics and personal care products, they are used as surfactants. Ceteareth-2 to -18 are used as emulsifying agents; Ceteareth-20 to -40 are used as solubilizing and cleansing agents; Ceteareth-22 is used as an emulsifying agent and a viscosity decreasing agent; and Ceteareth-50 to -100 are used as cleansing agents.